1. Field
The present disclosure relates to an apparatus and a method for manufacturing composite nanoparticles. More particularly, it relates to an apparatus and a method for manufacturing composite nanoparticles allowing manufacturing of composite nanoparticles of uniform size and high specific surface area without aggregation by performing gas phase synthesis in different stages using a U-shaped reaction chamber.
2. Description of the Related Art
Nanoparticles generally refer to fine particles sized between 1 nm and 100 nm. These nanoparticles have superior properties such as remarkably increased specific surface area, light weight, high strength, high toughness, etc. as compared to other materials. For this reason, the nanoparticles have enhanced surface activity as well as improved sinterability, thermal conductivity, etc.
Owing to the many advantages described above, the nanoparticles are widely studied and used in various fields, comprising ecology, energy, electronics, biology, and so forth. Recently, researches on composite nanoparticles synthesized from two or more different materials are carried out actively.
The methods for synthesizing nanoparticles may be classified into physical and chemical processes. In general, a wet method whereby an electric field or a laser is applied to an aqueous solution in which a precursor material is dispersed or another precursor material is added thereto is employed. Also, a technique of preparing nanoparticles by condensing molecules at a critical point of high temperature and pressure has been presented. For example, Korean Patent Publication No. 10-2009-0057262 discloses a wet method of synthesizing composite nanoparticles by hydrothermally treating amorphous hydrated metal oxide in the presence of titanium dioxide nanoparticles.
However, the existing wet method is problematic in that the manufacturing process is complicated and the control of particle shape, particle aggregation, pH, reaction temperature, reaction time, etc. is restricted, so highly advanced technology is required.
Accordingly, a gas phase synthesis method of vaporizing precursor materials at vapor pressure and synthesizing nanoparticles via interparticle collision in a high-temperature reactor is drawing attentions recently as an alternative to the wet method (solution method). This gas phase synthesis method is advantageous in that the selection of composition is widened since reaction with various gases can be used, the manufacturing process is simple and uniform nanoparticles can be synthesized with high purity.
For example, Korean Patent No. 10-0658113 discloses a process of synthesizing iron nanopowder coated with silica (SiO2) by chemical vapor condensation, Korean Patent Publication No. 10-2007-0017408 discloses an apparatus for producing nanoparticles by gas phase synthesis wherein heating units containing respective precursor materials are provided inside a reaction chamber, and Korean Patent Publication No. 10-2009-0109967 discloses a method and an apparatus for manufacturing aluminum nitride particles by gas phase synthesis by vaporizing precursor materials and introducing them into a reaction chamber.
In addition, the literature ‘Intraparticle structures of composite TiO2/SiO2 nanoparticles prepared by varying precursor mixing modes in vapor phase’ (Journal of Materials Science, Vol. 38, pp. 2619-2625, 2003) discloses a method of manufacturing a titania-silicon nanocomposite catalyst at high temperature by gas phase synthesis after inducing vaporization of precursor materials by applying vacuum inside a reactor. The literature ‘Preparation of anatase TiO2 supported on alumina by different metal organic chemical vapor deposition methods’ (Applied Catalysis A: General, Vol. 282, pp. 285-293, 2005) also discloses a technique of synthesizing titania-alumina nanoparticles from precursor materials using a high-temperature reactor.
However, the existing methods have the problem that, since the respective vaporized precursors are supplied to the reaction chamber through the same inlet, specific surface area of the nanoparticles decreases due to interparticle aggregation. Furthermore, the synthesized composite nanoparticles have low dispersity and large size. In addition, due to the restricted rate of supplying the precursors, a precise control is required and it is difficult to produce high-purity composite nanoparticles on a commercial scale.